In semiconductor fabrication, the necessary related equipment must often be tested and conditioned prior to being used to manufacture integrated circuits. Such testing and conditioning improve the quality and reliability of the manufactured integrated circuits by providing a preview of how the semiconductor manufacturing equipment operates during various processes. For example, “marathon experiments” are often conducted wherein a vast number of wafers are placed in a plasma chamber and etched in a conventional manner. Analysis of various device parameters and the end product during such marathon experiments provides information that is beneficial during the preparation for actual production of integrated circuits. In particular, data regarding particle emissions may be collected during the course of the marathon experiments to anticipate particle failure during the manufacture of integrated circuits.
To carryout such conditioning exercises and marathon experiments on semiconductor manufacturing equipment such as plasma chambers, standard test wafers are normally used in place of standard production wafers. A cross-section of a standard production wafer 10 and a standard test wafer 20 are shown in FIGS. 1 and 2, respectively. As shown, the standard test wafer 20 includes a wafer 22 including any type of materials thereon such as aluminum and the like. This standard test wafer 20 further has a layer of photoresist 24 thereon. By this structure, the standard test wafer 20 simulates a pair of uppermost layers 26 of the standard production wafer 10.
In order to properly simulate a standard production wafer 10, it is preferred that the photoresist 24 of the standard test wafer 20 be “patterned.” In other words, the resist is ideally applied to the standard test wafer 20 to define a plurality of vias, channels, etc. which in turn leave a percentage of the standard test wafer 20 exposed as shown in FIG. 3.
Therefore, the use of standard test wafers 20 can be expensive, especially when standard test wafers 20 have multiple layers similar to standard production wafers 10. This cost often fails to justify many conditioning exercises and marathon experiments which, in turn, leads to reduced quality and reliability during the subsequent processing of standard production wafers 10.
One known prior art alternative to the use of such “patterned” standard test wafers 20 is to alternate between aluminum wafers and blanket photoresist wafers in a plasma chamber. Such method, however, tends to be cumbersome and time consuming since the aluminum and blanket photoresist wafers must be alternated during use. Further, the aluminum wafers and blanket photoresist wafers are not processed at the same time. As such, the present method fails to effectively simulate the composition of materials being deposited in the plasma chamber during the processing of standard production wafers. This in turn gives rise to detrimental ramifications in particle performance.
There is thus a need for a test wafer that effectively simulates “patterned” standard test wafers and can be produced at a reduced cost.